That would definitely be the K series. It keeps the same layout (front intake, rear exhaust), doesn't have a turbo to consider, and it much closer in wiring type. Not to mention the whole direct injection needs to go along with the 1.5T.

I don't believe there is a single running 1.5T in any body style Fit yet. That project has to start with an entire donor car in my opinion because you're going to need the entire fuel system, ECU, wiring harness, etc.